For tense, I usually prefer past tenses, generally simple past. But it often moves into past perfect. Very rarely will I move into present perfect. I'm pretty sure the only time I use any of the other tenses is in dialogue. Simply because it reads a lot better when you say a character has done or did this as opposed to reading that they will do this, or are doing that, and expecting the other rpers to automatically convert that into, well, that's what the character did during that post. 

I actually find it rather strange when I read posts written in present or future, but future tenses are the weirdest to read. Although Clark's example of using present tense in a GM post makes sense, that I can get behind. But for character posts, it just feels weird. In present tense, everything's happening at once, despite the fact that there should be a clear sequence of events. And in future tense, it just seems like no one's sure these actions will actually happen, I always find myself wondering if there's a condition, like Character A will do this if ChAracter B does that, but Character A is supposedly reacting first and Character B's in the next post, following behind. And, yeah.... That's just how it reads to me.